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    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        /* 
        弹出年龄的案例
               1.询问年龄
                2.弹出年龄
        */
       var age =prompt("请问您今年几岁了");
       alert("今年"+age+"岁了");
    </script>
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